1. Field of the Invention
The invention relates to a perpendicular magnetic recording head and a magnetic recording unit mounted with the perpendicular magnetic recording head.
2. Description of Related Art
In recent years, along with an increased surface recording density in a magnetic recording medium (hereinafter, referred to as a “recording medium”) represented by a hard disk, a perpendicular magnetic recording system in which a direction of a signal magnetic field is set to a direction intersecting with a surface of the recording medium is a main stream as a recording system of a magnetic recording head. This is because a line recording density thereof is advantageously higher than that in a longitudinal magnetic recording system in related art, and a recorded recording medium is advantageously less affected by thermal fluctuation.
A magnetic recording head of the perpendicular magnetic recording system (hereinafter, referred to as “perpendicular magnetic recording head”) has a main magnetic pole that guides a magnetic flux generated in a thin film coil to a recording medium, and the main magnetic pole has a tip section (a magnetic pole) that emits a magnetic flux to generate a recording magnetic field (a perpendicular magnetic field) and has a narrow width.
In these days, demand to further improve the surface recording density of the magnetic recording medium shows tendency to further increase. Under such circumstances, to obtain recording performance of the perpendicular magnetic recording head stably, for example, it is necessary to suppress WATE (wide adjacent track erase) effective magnetic field as much as possible. This is because, if the WATE effective magnetic field is not sufficiently suppressed, defect in which information recorded in adjacent tracks is unintentionally overwritten with false information may occur. The WATE effective magnetic field means effective magnetic field affecting adjacent tracks within a wide range (for example, two to ten tracks adjacent to a track to be written), out of recording magnetic field emitted from an air bearing surface toward the magnetic recording medium.
To achieve the above-described suppression, there is proposed a configuration in which a shield is so provided as to surround right, left, top, and bottom of the main magnetic pole or a magnetic circuit is provided both on a trailing side of the main magnetic pole and a leading side of the main magnetic pole (for example, U.S. Patent Application Publication No. 2005/0068678 specification). Further, there is also proposed a configuration in which part exposed on the air bearing surface is limited, and the magnetic circuit is partially distanced from the air bearing surface.
However, the configuration as described above causes complexity in manufacturing process thereof in many cases. Further, in a case of a configuration in which a part of a leading shield is recessed from the air bearing surface, the length of the magnetic path on the leading side becomes long, which causes degradation in magnetization efficiency. Moreover, when a magnetic circuit exists on the leading side, many of the magnetic flux of the recording magnetic field emitted from the main magnetic pole returns to the leading shield, which may cause deterioration in recording performance.
Based on these backgrounds, it is desirable to provide a perpendicular magnetic recording head and a magnetic recording unit that are capable of dealing with higher density recording while suppressing incorrect writing to adjacent tracks, and is excellent in manufacturability.